000 AXNT20 KNHC 270006 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 806 PM EDT MON SEP 26 2016 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...SPECIAL FEATURES... A vigorous tropical wave is in the central Atlantic associated with a 1008 mb low centered near 10N48W. The wave extends from 05N to 15N with axis near 48W, moving W at 20-25 kt over the past 24 hours. Abundant moisture at the low and middle levels, and a diffluent environment aloft support scattered heavy showers and tstms N of the low center from 10N to 17N between 44W and 53W. Similar trailing convection is from 11N to 16N between 34W and 44W. Environmental conditions remain conducive for development, and a tropical depression is likely to form during the next day or two while the system moves W-NW. Interests in the eastern and central Caribbean Sea, including the northern coast of South America, should monitor the progress of this system. Regardless of development, heavy rains and strong gusty winds, possibly to tropical storm force, are expected to spread over the Windward Islands and portions of the southern Lesser Antilles beginning late Tuesday or Wednesday. The chance of formation of this system within the next 48 hours is high. Please see the Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... A tropical wave is E of the Cabo Verde Islands extending from 06N to 16N with axis near 18W, moving at 5 kt over the past 24 hours. The wave is in a region of favorable deep layer wind shear, however CIRA LPW from surface to 850 mb show pockets of dry air in its environment, which in part is suppressing convection at the time. A tropical wave is in the E Caribbean extending from 10N to 19N with axis near 68W, moving W at 15 kt over the past 24 hours. Unfavorable deep layer wind shear and strong dry air subsidence from aloft hinder convection at the time. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 09N13W to 08N30W to 09N48W to 07N54W. Aside from the convection associated with the tropical wave discussed in the special features section, scattered showers are from 06N to 11N between 21W and 25W and heavy showers are within 90 nm off the coast of Liberia, Africa. ...DISCUSSION... GULF OF MEXICO... Generally low pressure dominates across the basin, being the main feature an elongated surface trough that extends from Texas adjacent waters near 27N95W to the Bay of Campeche near 19N95W. Abundant low level moisture advected from the Caribbean by SE to E flow along with middle to upper level diffluent support scattered showers S of 26N W of 90W and heavy showers and tstms over the Yucatan Peninsula and northern Guatemala. At the upper levels, a broad ridge covers the basin W of 86W while the base of an upper trough reaches the NW coast of Cuba. Diffluence between these two upper level features is supporting scattered showers and tstms across the Florida Peninsula and Gulf waters E of 86W. A weak frontal boundary will move across the northern Gulf through Tuesday night. A stronger cold front will push into the north Gulf Thursday. CARIBBEAN SEA... An upper trough extends along the Florida Peninsula to a base over NW Cuba. Diffluent flow between a broad upper ridge covering great portions of the Gulf of Mexico and this trough support scattered heavy showers and tstms along Cuba and adjacent waters. On the other hand, middle level diffluence support heavy showers and tstms over central Haiti and far west-central Dominican Republic. A weak tropical wave is moving towards the central Caribbean tonight. The wave may amplify the convection over Hispaniola tonight. Fair weather is elsewhere being supported by unfavorable deep layer wind shear and strong dry air subsidence. Otherwise, gentle to moderate trades dominate the basin, except off the Gulf of Venezuela and northern Colombia coastal waters where fresh to locally strong winds are possible. A vigorous tropical wave with high potential of becoming a tropical cyclone within the next two days will generate gale force winds over the SE Caribbean Wednesday. Regardless of development, this system will carry heavy rain to affect mainly the Windward Islands Wed to Thu. ...HISPANIOLA... Middle level diffluence support heavy showers and tstms over central Haiti and far west-central Dominican Republic. A weak tropical wave is moving towards the central Caribbean tonight. The wave may amplify the convection over Hispaniola tonight. ATLANTIC OCEAN... The main feature in the basin is a vigorous tropical wave with high chances of becoming a tropical cyclone within the next two days. See special features for more details. A broad area of diffluent flow aloft with base over NW Cuba support scattered showers across the Straits of Florida and the SW Atlc W of 70W. Farther east, a weak stationary front extends from 30N60W to a 1015 mb low from which a surface trough extends SW to 28N70W. Otherwise, surface ridging dominates elsewhere in the central and eastern Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS